1. Field of the Invention
The present invention relates to a stereoscopic display device and control method therefor, and more particularly, to a head-mounted type stereoscopic display device and control method therefor.
2. Description of the Related Art
In recent years, as a technology for fusing real and virtual worlds in real time and seamlessly, a Mixed Reality (MR) technology is known.
In addition, as a device for experiencing Mixed Reality, a stereoscopic video see-through HMD (Head Mounted Display) is known. A stereoscopic video see-through HMD is a device that displays stereoscopic images in front of the eyes of the wearer. When composite images, in which three-dimensional virtual images seen from the viewpoint position of the wearer are superimposed on stereoscopic video images that are substantially the same as those seen when the user is not wearing the HMD, are generated and presented to the HMD, the wearer experiences a feeling just like that in which virtual objects appear to be present in real space. That is Mixed Reality.
It should be noted that, in general, virtual object images are usually implemented by CG (Computer Graphics). In addition, stereoscopic video images are usually sensed by a stereoscopic video camera attached to the HMD.
FIG. 2 is a schematic diagram showing a state of attachment of a stereoscopic video see-through HMD 400. The video see-through HMD 400 has the external appearance of eyeglasses or goggles, inside of which a display device for the right eye 402R and a display device for the left eye 402L, composed for example of LCDs, are disposed. In addition, where the stereoscopic video images are acquired by video cameras attached to the HMD, for example, stereoscopic video cameras 401R, 401L are mounted at positions near the viewpoint position of the wearer.
In order to create this experience of Mixed Reality, it is necessary to supply a three-dimensional image. In order to do that, it is necessary to input a composite image for the left eye and a composite image for the right eye, generated by inputting images sensed with two video cameras (left and right) to an image processing apparatus and superimposing virtual object images thereon, correctly to HMD left- and right-display devices.
However, because in an actual environment cables other than video signal cables are also connected between the image processing apparatus and the HMD (for example, HMD power supply cables as well as position and orientation sensor cables), the cables for each of the left and the right are sometimes connected incorrectly.
In the case of stereoscopic images, if the image for the left eye and the image for the right eye are displayed in reverse, not only is the result not recognizable as a three-dimensional image but also the observer experiences eye strain. For example, in the field of single-lens-reflex cameras, a technology has been proposed that determines whether or not the lens that is installed has the proper compatibility (Japanese Patent Laid-Open No. 2003-228115). However, a single-lens-reflex camera is very different from a stereoscopic HMD and the problem of mistaking left and right does not arise. Moreover, interchangeable lenses and video input connections are completely different in their structure and their purpose.
Thus, as described above, conventionally, there has been no mechanism for aiding the user in correctly inputting left and right image signals to a head-mounted type stereoscopic display device.